Synthesis of shape-controlled NiO–graphene nanocomposites with enhanced supercapacitive properties

Abstract

Flowerlike and polyhedral NiO–graphene nanocomposites have been successfully synthesized using a facile hydrothermal method. The formation mechanism of the two nanocomposites with different morphologies has been studied. The resulting products are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopic analysis (XPS), thermogravimetry (TG), and the Brunauer–Emmett–Teller (BET) method. The prepared NiO–graphene nanocomposites with different shapes can be used for supercapacitor electrode materials. Through electrochemical tests, the flowerlike NiO–graphene composite shows higher specific capacitance than that of the polyhedral one with a specific capacitance as high as 500 F g⁻¹ at a scan rate of 5 mV s⁻¹ while the polyhedral NiO–graphene composite delivers better long-term cycle stability with 84% specific capacitance remaining after 3000 cycles in a 1 M KOH electrolyte.